port question

the pic is kinda hard to see...sorry but this is what i'm proposing...2-15's in my car the 20" tall is towards the back. and the 18"tall angled part sits agains my back seat, and the baffle is gonna be angled toward the front by 2 inches. well the question is the port...see the light blue...its gonna be on the baffle on the side, but where it exits will be at an angle...see what i mean. how do i acount for the angle when i'm figuring my port length? its gonna be a 2" differance from one side to the other so should i just take off 1" from my port length and start measuring the rest of the port @ the 18" side? does this look like a good design for 2-15's. i'm planning on getting 2RL-p's. i came up with 6.252ft^2 with 93.25in^2 port @ 28Hz.